Method for making chlorohydrin in corrosion-resistant equipment

ABSTRACT

Process for preparing a chlorohydrin, comprising a step in which a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof is subjected to reaction with a chlorinating agent containing hydrogen chloride and at least one other step, carried out in apparatus made from or covered with materials which are resistant to the chlorinating agent under the conditions in which this step is realized.

The present patent application is a 371 of PCT/EP2006/062447 filed May 19, 2006. In addition, this application claims the benefit of patent application FR 05.05120 and of patent application EP 05104321.4, both filed on 20 May 2005, and of provisional U.S. patent applications 60/734,659, 60/734,627, 60/734,657, 60/734,658, 60/734,635, 60/734,634, 60/734,637 and 60/734,636, all filed on 8 Nov. 2005, the content of all of which is incorporated here by reference.

The present invention relates to a process for preparing a chlorohydrin. It relates more specifically to a process for preparing a chlorohydrin in apparatus made from materials which are resistant to corrosion.

Chlorohydrins are reaction intermediates in the preparation of epoxides and derived products. Dichloropropanol, for example, is a reaction intermediate in the preparation of epichlorohydrin and of epoxy resins (Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, 1992, Vol. 2, page 156, John Wiley & Sons, Inc.).

According to known processes it is possible to obtain dichloropropanol in particular by hypochlorinating allyl chloride, by chlorinating allyl alcohol and by hydrochlorinating glycerol. This latter process has the advantage that the dichloropropanol can be obtained starting from fossil raw materials or from renewable raw materials, and it is known that natural petrochemical resources, from which the fossil materials are obtained, such as petroleum, natural gas or coal, for example, are limited in their terrestrial availability.

Application WO 2005/054167 of SOLVAY SA describes a process for preparing dichloropropanol by reacting glycerol with hydrogen chloride in the presence of an acid such as adipic acid as catalyst. The reaction is carried out in a reactor fabricated from or covered with a material which is resistant to the chlorinating agent under the reaction conditions. The use of this type of material is limited, however, to the reactor for chlorinating the glycerol.

The invention provides a process for preparing a chlorohydrin, comprising:

-   (a) a step in which a polyhydroxylated aliphatic hydrocarbon, an     ester of a polyhydroxylated aliphatic hydrocarbon or a mixture     thereof is subjected to reaction with a chlorinating agent     containing hydrogen chloride -   (b) at least one other step, carried out in apparatus made from or     covered with materials which are resistant to the chlorinating agent     under the conditions in which this step is realized.

It has been found that, in the process according to the invention, the following advantages are realized:

-   (a) the life of the apparatus is prolonged -   (b) the management of the streams in the process is simplified -   (c) the overall cost of the process is reduced -   (d) the processes downstream of the process for preparing the     chlorohydrin, such as, for example, the purge treatment by     high-temperature oxidation, which requires low metal contents, are     not disrupted -   (e) the quality of the aqueous effluent from an epoxide preparation     which is supplied with mixtures of chlorohydrin and water obtained     from the process for chlorinating the polyhydroxylated aliphatic     hydrocarbon is not adversely affected by an abnormally high metal     content and, consequently, it is not necessary to carry out a     special purification treatment on the aqueous discharges for the     purpose of reducing their metal content.

It has in fact been found, surprisingly, that corrosion phenomena may be produced in the process other than in the step of chlorinating the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof, and may have an unfavourable overall impact on the economics of the process.

The invention further provides, accordingly, for the use of apparatus made from or covered with materials which are resistant to the chlorinating agents in a process for preparing a chlorohydrin comprising a step in which a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof is subjected to reaction with a chlorinating agent containing hydrogen chloride, in at least one step other than the reaction step.

The reason for this that it has been found that the use of this type of apparatus makes it possible to prevent the corrosion by hydrogen chloride in the presence of water and of the polyhydroxylated aliphatic hydrocarbon. The water may be water generated by the reaction between the polyhydroxylated aliphatic hydrocarbon and the chlorinating agent, or water introduced into the process.

The invention provides, finally, plant for preparing a chlorohydrin, comprising

-   (a) one part in which a polyhydroxylated aliphatic hydrocarbon, an     ester of a polyhydroxylated aliphatic hydrocarbon or a mixture     thereof is subjected to reaction with a chlorinating agent     containing hydrogen chloride -   (b) at least one other part made in apparatus made from or covered     with materials which are resistant to the chlorinating agent.

The term “polyhydroxylated aliphatic hydrocarbon” refers to a hydrocarbon which contains at least two hydroxyl groups attached to two different saturated carbon atoms. The polyhydroxylated aliphatic hydrocarbon may contain, but is not limited to, from 2 to 60 carbon atoms.

Each of the carbons of a polyhydroxylated aliphatic hydrocarbon bearing the hydroxyl functional group (OH) cannot possess more than one OH group and must have sp3 hybridization. The carbon atom carrying the OH group may be primary, secondary or tertiary. The polyhydroxylated aliphatic hydrocarbon used in the present invention must contain at least two sp3-hybridized carbon atoms carrying an OH group. The polyhydroxylated aliphatic hydrocarbon includes any hydrocarbon containing a vicinal diol (1,2-diol) or a vicinal triol (1,2,3-triol), including the higher, vicinal or contiguous orders of these repeating units. The definition of the polyhydroxylated aliphatic hydrocarbon also includes, for example, one or more 1,3-, 1,4-, 1,5- and 1,6-diol functional groups. The polyhydroxylated aliphatic hydrocarbon may also be a polymer such as polyvinyl alcohol. Geminal diols, for example, are excluded from this class of polyhydroxylated aliphatic hydrocarbons.

The polyhydroxylated aliphatic hydrocarbons may contain aromatic moieties or heteroatoms, including, for example, heteroatoms of halogen, sulphur, phosphorus, nitrogen, oxygen, silicon and boron type, and mixtures thereof.

Polyhydroxylated aliphatic hydrocarbons which can be used in the present invention comprise, for example, 1,2-ethanediol (ethylene glycol), 1,2-propanediol (propylene glycol), 1,3-propanediol, 1-chloro-2,3-propanediol (chloropropanediol), 2-chloro-1,3-propanediol (chloropropanediol), 1,4-butanediol, 1,5-pentanediol, cyclohexanediols, 1,2-butanediol, 1,2-cyclohexanedimethanol, 1,2,3-propanetriol (also known as “glycerol” or “glycerin”), and mixtures thereof. With preference the polyhydroxylated aliphatic hydrocarbon used in the present invention includes, for example, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, chloropropanediol and 1,2,3-propanetriol, and mixtures of at least two thereof. More preferably the polyhydroxylated aliphatic hydrocarbon used in the present invention includes, for example, 1,2-ethanediol, 1,2-propanediol, chloropropanediol and 1,2,3-propanetriol, and mixtures of at least two thereof. 1,2,3-Propanetriol or glycerol is the most preferred.

The esters of polyhydroxylated aliphatic hydrocarbon may be present in the polyhydroxylated aliphatic hydrocarbon and/or may be produced in the process for preparing the chlorohydrin and/or may be prepared prior to the process for preparing the chlorohydrin. Examples of esters of the polyhydroxylated aliphatic hydrocarbon comprise ethylene glycol monoacetate, propanediol monoacetates, glycerol monoacetates, glycerol monostearates, glycerol diacetates and mixtures thereof.

The term “chlorohydrin” is used here in order to describe a compound containing at least one hydroxyl group and at least one chlorine atom attached to different saturated carbon atoms. A chlorohydrin which contains at least two hydroxyl groups is also a polyhydroxylated aliphatic hydrocarbon. Accordingly the starting material and the product of the reaction may each be chlorohydrins. In that case the “product” chlorohydrin is more chlorinated than the starting chlorohydrin, in other words has more chlorine atoms and fewer hydroxyl groups than the starting chlorohydrin. Preferred chlorohydrins are chloroethanol, chloropropanol, chloropropanediol, dichloropropanol and mixtures of at least two thereof. Dichloropropanol is particularly preferred. Chlorohydrins which are more particularly preferred are 2-chloroethanol, 1-chloropropan-2-ol, 2-chloropropan-1-ol, 1-chloropropane-2,3-diol, 2-chloropropane-1,3-diol, 1,3-dichloropropan-2-ol, 2,3-dichloropropan-1-ol and mixtures of at least two thereof.

The polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon, or the mixture thereof in the process according to the invention may be obtained starting from fossil raw materials or starting from renewable raw materials, preferably starting from renewable raw materials.

By fossil raw materials are meant materials obtained from the processing of petrochemical natural resources, such as petroleum, natural gas and coal, for example. Among these materials preference is given to organic compounds containing 2 and 3 carbon atoms. When the polyhydroxylated aliphatic hydrocarbon is glycerol, allyl chloride, allyl alcohol and “synthetic” glycerol are particularly preferred. By “synthetic” glycerol is meant a glycerol generally obtained from petrochemical resources. When the polyhydroxylated aliphatic hydrocarbon is ethylene glycol, ethylene and “synthetic” ethylene glycol are particularly preferred. By “synthetic” ethylene glycol is meant an ethylene glycol generally obtained from petrochemical resources. When the polyhydroxylated aliphatic hydrocarbon is propylene glycol, propylene and “synthetic” propylene glycol are particularly preferred. By “synthetic” propylene glycol is meant a propylene glycol generally obtained from petrochemical resources.

By renewable raw materials are meant materials obtained from the processing of renewable natural resources. Among these materials preference is given to “natural” ethylene glycol, “natural” propylene glycol and “natural” glycerol. “Natural” ethylene glycol, propylene glycol and glycerol are obtained for example by conversion of sugars by thermochemical processes, it being possible for these sugars to be obtained starting from biomass, as described in “Industrial Bioproducts: Today and Tomorrow”, Energetics, Incorporated for the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Office of the Biomass Program, July 2003, pages 49, 52 to 56. One of these processes is, for example, the catalytic hydrogenolysis of sorbitol obtained by thermochemical conversion of glucose. Another process is, for example, the catalytic hydrogenolysis of xylitol obtained by hydrogenation of xylose. The xylose may for example be obtained by hydrolysis of the hemicellulose present in maize fibres. By “glycerol obtained from renewable raw materials” is meant, in particular, glycerol obtained during the production of biodiesel or else glycerol obtained during conversions of animal or vegetable oils or fats in general, such as saponification, transesterification or hydrolysis reactions.

Among the oils which can be used in the process of the invention, mention may be made of all common oils, such as palm oil, palm kernel oil, copra oil, babassu oil, former or new (low erucic acid) colza oil, sunflower oil, maize oil, castor oil and cotton oil, peanut oil, soya bean oil, linseed oil and crambe oil, and all oils obtained, for example, from sunflower plants or colza plants obtained by genetic modification or hybridization.

It is also possible to employ used frying oils, various animal oils, such as fish oils, tallow, lard and even squaring greases.

Among the oils used mention may also be made of oils which have been partly modified by means, for example, of polymerization or oligomerization, such as, for example, the “stand oils” of linseed oil and of sunflower oil, and blown vegetable oils.

A particularly suitable glycerol may be obtained during the conversion of animal fats. Another particularly suitable glycerol may be obtained during the production of biodiesel. A third, very suitable glycerol may be obtained during the conversion of animal or vegetable oils or fats by transesterification in the presence of a heterogeneous catalyst, as described in documents FR 2752242, FR 2869612 and FR 2869613. More specifically, the heterogeneous catalyst is selected from mixed oxides of aluminium and zinc, mixed oxides of zinc and titanium, mixed oxides of zinc, titanium and aluminium, and mixed oxides of bismuth and aluminium, and the heterogeneous catalyst is employed in the form of a fixed bed. This latter process can be a process for producing biodiesel.

In the process for preparing a chlorohydrin according to the invention, the polyhydroxylated aliphatic hydrocarbon may be as described in the patent application entitled “Process for preparing chlorohydrin by converting polyhydroxylated aliphatic hydrocarbons”, filed in the name of SOLVAY SA on the same day as the present application, and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrin wherein a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof whose total metal content, expressed in elemental form, is greater than or equal to 0.1 μg/kg and less than or equal to 1000 mg/kg is reacted with a chlorinating agent.

In the process according to the invention it is preferred to use glycerol obtained starting from renewable raw materials.

In the process for preparing a chlorohydrin according to the invention, the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof may be a crude product or a purified product, such as are specifically disclosed in application WO 2005/054167 of SOLVAY SA, from page 2 line 8 to page 4 line 2.

In the process for preparing a chlorohydrin according to the invention, the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof may be a polyhydroxylated aliphatic hydrocarbon whose alkali metal and/or alkaline earth metal content is less than or equal to 5 g/kg, as described in the application entitled “Process for preparing a chlorohydrin by chlorinating a polyhydroxylated aliphatic hydrocarbon”, filed in the name of SOLVAY SA on the same day as the present application, and whose content is incorporated here by reference. The alkali metals may be selected from lithium, sodium, potassium, rubidium and cesium and the alkaline earth metals may be selected from magnesium, calcium, strontium and barium.

In the process according to the invention, the alkali metal and/or alkaline earth metal content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is less than or equal to 5 g/kg, often less than or equal to 1 g/kg, more particularly less than or equal to 0.5 g/kg and in certain cases less than or equal to 0.01 g/kg. The alkali metal and/or alkaline earth metal content of the glycerol is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention the alkali metals are generally lithium, sodium, potassium and cesium, often sodium and potassium, and frequently sodium.

In the process for preparing a chlorohydrin according to the invention, the lithium content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is generally less than or equal to 1 g/kg, often less than or equal to 0.1 g/kg and more particularly less than or equal to 2 mg/kg. This content is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention, the sodium content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is generally less than or equal to 1 g/kg, often less than or equal to 0.1 g/kg and more particularly less than or equal to 2 mg/kg. This content is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention, the potassium content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is generally less than or equal to 1 g/kg, often less than or equal to 0.1 g/kg and more particularly less than or equal to 2 mg/kg. This content is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention, the rubidium content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is generally less than or equal to 1 g/kg, often less than or equal to 0.1 g/kg and more particularly less than or equal to 2 mg/kg. This content is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention, the cesium content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is generally less than or equal to 1 g/kg, often less than or equal to 0.1 g/kg and more particularly less than or equal to 2 ng/kg. This content is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention the alkaline earth metal elements are generally magnesium, calcium, strontium and barium, often magnesium and calcium and frequently calcium.

In the process according to the invention, the magnesium content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is generally less than or equal to 1 g/kg, often less than or equal to 0.1 g/kg and more particularly less than or equal to 2 mg/kg. This content is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention, the calcium content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is generally less than or equal to 1 g/kg, often less than or equal to 0.1 g/kg and more particularly less than or equal to 2 ng/kg. This content is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention, the strontium content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is generally less than or equal to 1 g/kg, often less than or equal to 0.1 g/kg and more particularly less than or equal to 2 ng/kg. This content is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention, the barium content of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof is generally less than or equal to 1 g/kg, often less than or equal to 0.1 g/kg and more particularly less than or equal to 2 ng/kg. This content is generally greater than or equal to 0.1 μg/kg.

In the process according to the invention the alkali and/or alkaline earth metals are generally present in the form of salts, frequently in the form of chlorides, sulphates and mixtures thereof. Sodium chloride is the most often encountered.

In the process for preparing a chlorohydrin according to the invention, the chlorinating agent may be as described in application WO 2005/054167 of SOLVAY SA, from page 4 line 25 to page 6 line 2.

In the process for preparing a chlorohydrin according to the invention, the chlorinating agent may be hydrogen chloride as described in application WO 2005/054167 or SOLVAY SA, from page 4 line 30 to page 6 line 2.

Particular mention is made of a chlorinating agent which may be aqueous hydrochloric acid or hydrogen chloride which is preferably anhydrous.

The hydrogen chloride may originate from a process of pyrolysing organic chlorine compounds, such as, for example, from vinyl chloride preparation, from a process for preparing 4,4-methylenediphenyl diisocyanate (MDI) or toluene diisocyanate (TDI), from metal pickling processes or from the reaction of an inorganic acid such as sulphuric or phosphoric acid with a metal chloride such as sodium chloride, potassium chloride or calcium chloride.

In one advantageous embodiment of the process for preparing a chlorohydrin according to the invention, the chlorinating agent is gaseous hydrogen chloride or an aqueous solution of hydrogen chloride, or a combination of the two.

In the process for preparing a chlorohydrin according to the invention, the hydrogen chloride may be an aqueous solution of hydrogen chloride or hydrogen chloride which is preferably anhydrous, obtained from plant for preparing allyl chloride and/or for preparing chloromethanes and/or chloronolysis and/or plant for high-temperature oxidation of chlorine compounds, as described in the application entitled “Process for preparing a chlorohydrin by reacting a polyhydroxylated aliphatic hydrocarbon with a chlorinating agent”, filed in the name of SOLVAY SA on the same day as the present application, and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrin from a polyhydroxylated aliphatic hydrocarbon, from an ester of a polyhydroxylated aliphatic hydrocarbon or from a mixture thereof, and from a chlorinating agent, the chlorinating agent comprising at least one of the following compounds: nitrogen, oxygen, hydrogen, chlorine, an organic hydrocarbon compound, an organic halogen compound, an organic oxygen compound and a metal.

Particular mention is made of an organic hydrocarbon compound selected from saturated and unsaturated aliphatic and aromatic hydrocarbons and mixtures thereof.

Particular mention is made of an unsaturated aliphatic hydrocarbon selected from acetylene, ethylene, propylene, butene, propadiene, methylacetylene and mixtures thereof, of a saturated aliphatic hydrocarbon selected from methane, ethane, propane, butane and mixtures thereof and of an aromatic hydrocarbon which is benzene.

Particular mention is made of an organic halogen compound which is an organic chlorine compound selected from chloromethanes, chloroethanes, chloropropanes, chlorobutanes, vinyl chloride, vinylidene chloride, monochloropropenes, perchloroethylene, trichloroethylene, chlorobutadienes, chlorobenzenes and mixtures thereof.

Particular mention is made of an organic halogen compound which is an organic fluorine compound selected from fluoromethanes, fluoroethanes, vinyl fluoride, vinylidene fluoride and mixtures thereof.

Particular mention is made of an organic oxygen compound selected from alcohols, chloroalcohols, chloroethers and mixtures thereof.

Particular mention is made of a metal selected from alkali metals, alkaline earth metals, iron, nickel, copper, lead, arsenic, cobalt, titanium, cadmium, antimony, mercury, zinc, selenium, aluminium, bismuth and mixtures thereof.

Mention is made more particularly of a process wherein the chlorinating agent originates, at least partially from a process for preparing allyl chloride and/or a process for preparing chloromethanes and/or a process for chlorinolysis and/or a process for oxidizing chlorine compounds at a temperature greater than or equal to 800° C.

In one particularly advantageous embodiment of the process for preparing a chlorohydrin according to the invention, the hydrogen chloride is an aqueous solution of hydrogen chloride and does not contain gaseous hydrogen chloride.

In the process for preparing a chlorohydrin according to the invention, the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof with the chlorinating agent may be carried out in a reactor as described in application WO 2005/054167 of SOLVAY SA on page 6 lines 3 to 23.

Mention is made particularly of plant made from or covered with materials which are resistant under the reaction conditions to the chlorinating agents, particularly to the hydrogen chloride. Mention is made more particularly of plant made from enameled steel or from tantalum.

In the process for preparing dichloropropanol according to the invention, the reaction of the glycerol with the hydrogen chloride may be carried out in a reaction medium as described in the application entitled “Continuous process for preparing chlorohydrins”, filed in the name of SOLVAY SA on the same day as the present application, and the content of which is incorporated here by reference.

Particular mention is made of a continuous process for producing chlorohydrin in which a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof is reacted with a chlorinating agent and an organic acid in a liquid reaction medium whose steady-state composition comprises polyhydroxylated aliphatic hydrocarbon and esters of polyhydroxylated aliphatic hydrocarbon for which the sum of the amounts, expressed in moles of polyhydroxylated aliphatic hydrocarbon, is greater than 1.1 mol % and less than or equal to 30 mol %, the percentage being based on the organic part of the liquid reaction medium.

The organic part of the liquid reaction medium consists of all of the organic compounds of the liquid reaction medium, in other words the compounds whose molecule contains at least one carbon atom.

In the process for preparing a chlorohydrin according to the invention, the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof and the chlorinating agent may be carried out in the presence of a catalyst as described in application WO 2005/054167 of SOLVAY SA from page 6 line 28 to page 8 line 5.

Mention is made particularly of a catalyst based on a carboxylic acid or on a carboxylic acid derivative having an atmospheric boiling point of greater than or equal to 200° C., especially adipic acid and derivatives of adipic acid.

In the process for preparing a chlorohydrin according to the invention, the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof and the chlorinating agent may be carried out at a catalyst concentration, temperature and pressure and for residence times as described in the application WO 2005/054167 of SOLVAY SA from page 8 line 6 to page 10 line 10.

Mention is made particularly of a temperature of at least 20° C. and not more than 160° C., of a pressure of at least 0.3 bar and not more than 100 bar and of a residence time of at least 1 h and not more than 50 h.

In the process for preparing a chlorohydrin according to the invention, the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof with the chlorinating agent may be carried out in the presence of a solvent as described in application WO 2005/054167 of SOLVAY SA at page 11 lines 12 to 36.

Mention is made particularly of organic solvents such as a chlorinated organic solvent, an alcohol, a ketone, an ester or an ether, a non-aqueous solvent which is miscible with the polyhydroxylated aliphatic hydrocarbon, such as chloroethanol, chloropropanol, chloropropanediol, dichloropropanol, dioxane, phenol, cresol and mixtures of chloropropanediol and dichloropropanol, or heavy products of the reaction such as at least partially chlorinated and/or esterified oligomers of the polyhydroxylated aliphatic hydrocarbon.

In the process for preparing a chlorohydrin according to the invention, the reaction of the polyhydroxylated aliphatic hydrocarbon with the chlorinating agent may be carried out in the presence of a liquid phase comprising heavy compounds other than the polyhydroxylated aliphatic hydrocarbon, as described in the application entitled “Process for preparing a chlorohydrin in a liquid phase”, filed in the name of SOLVAY SA on the same day as the present application, and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrin wherein a polyhydroxylated aliphatic hydrocarbon, an ester of polyhydroxylated aliphatic hydrocarbon or a mixture thereof is subjected to reaction with a chlorinating agent in the presence of a liquid phase comprising heavy compounds other than the polyhydroxylated aliphatic hydrocarbon and having a boiling temperature under a pressure of 1 bar absolute of at least 15° C. more than the boiling temperature of the chlorohydrin under a pressure of 1 bar absolute.

In the process for preparing the epoxide according to the invention the reaction of the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof with the chlorinating agent is preferably carried out in a liquid reaction medium. The liquid reaction medium may be a single-phase or multi-phase medium.

The liquid reaction medium is composed of all of the dissolved or dispersed solid compounds, dissolved or dispersed liquid compounds and dissolved or dispersed gaseous compounds at the temperature of the reaction.

The reaction medium comprises the reactants, the catalyst, the solvent, the impurities present in the reactants, in the solvent and in the catalyst, the reaction intermediates, the products and the by-products of the reaction.

By reactants are meant the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon and the chlorinating agent.

Among the impurities present in the polyhydroxylated aliphatic hydrocarbon mention may be made of carboxylic acids, salts of carboxylic acids, esters of fatty acid with the polyhydroxylated aliphatic hydrocarbon, esters of fatty acids with the alcohols used in the transesterification, and inorganic salts such as alkali metal or alkaline earth metal sulphates and chlorides.

When the polyhydroxylated aliphatic hydrocarbon is glycerol, the impurities in the glycerol that may be mentioned include carboxylic acids, salts of carboxylic acids, fatty acid esters such as mono-, di- and triglycerides, esters of fatty acids with the alcohols used in the transesterification and inorganic salts such as alkali metal or alkaline earth metal sulphates and chlorides.

Among the reaction intermediates mention may be made of monochlorohydrins of the polyhydroxylated aliphatic hydrocarbon and their esters and/or polyesters, the esters and/or polyesters of the polyhydroxylated aliphatic hydrocarbon and the esters of polychlorohydrins.

When the chlorohydrin is dichloropropanol, the reaction intermediates that may be mentioned include glycerol monochlorohydrin and its esters and/or polyesters, the esters and/or polyesters of glycerol and the esters of dichloropropanol.

The ester of polyhydroxylated aliphatic hydrocarbon may therefore be, at each instance, a reactant, an impurity of the polyhydroxylated aliphatic hydrocarbon or a reaction intermediate.

By products of the reaction are meant the chlorohydrin and water. The water may be the water formed in the chlorination reaction and/or water introduced into the process, for example via the polyhydroxylated aliphatic hydrocarbon and/or the chlorinating agent, as described in the application WO 2005/054167 of SOLVAY SA at page 2 lines 22 to 28 to page 3 lines 20 to 25, at page 5 lines 7 to 31 and at page 12 lines 14 to 19.

Among the by-products mention may be made for example of the partially chlorinated and/or esterified oligomers of the polyhydroxylated aliphatic hydrocarbon.

When the polyhydroxylated aliphatic hydrocarbon is glycerol, the by-products that may be mentioned include, for example, the partially chlorinated and/or esterified oligomers of glycerol.

The reaction intermediates and the by-products may be formed in the different steps of the process, such as, for example, during the step of preparing the chlorohydrin and during the steps of separating off the chlorohydrin.

The liquid reaction mixture may therefore contain the polyhydroxylated aliphatic hydrocarbon, the chlorinating agent in solution or dispersion in the form of bubbles, the catalyst, the solvent, the impurities present in the reactants, in the solvent and in the catalyst, such as dissolved or solid salts, for example, the reaction intermediates, the products and the by-products of the reaction.

Steps (a) and (b) of the process according to the invention may be carried out in batch mode or in continuous mode. Preference is given to carrying out all of the steps in continuous mode.

In the process according to the invention, the separation of the chlorohydrin and of the other compounds from the reaction mixture may be carried out in accordance with the methods as described in the application WO 2005/054167 of SOLVAY SA from page 12 line 1 to page 16 line 35 and page 18 lines 6 to 13. These other compounds are those mentioned above and include unconsumed reactants, the impurities present in the reactants, the catalyst, the solvent, the reaction intermediates, the water and the by-products of the reaction.

Particular mention is made of separation by azeotropic distillation of a water/chlorohydrin/chlorinating agent mixture under conditions which minimize the losses of chlorinating agent, followed by isolation of the chlorohydrin by phase separation.

In the process for preparing a chlorohydrin according to the invention, the isolation of the chlorohydrin and of the other compounds from the reaction mixture may be carried out in accordance with methods of the kind described in patent application EP 05104321.4, filed in the name of SOLVAY SA on 20/05/2005 and the content of which is incorporated here by reference. Particular mention is made of a separation method including at least one separating operation intended to remove the salt from the liquid phase.

Particular mention is made of a process for preparing a chlorohydrin by reacting a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof with a chlorinating agent wherein the polyhydroxylated aliphatic hydrocarbon, an ester of the polyhydroxylated aliphatic hydrocarbon or a mixture thereof that is used comprises at least one solid or dissolved metal salt, the process including a separation operation intended to remove part of the metal salt. Mention is made more particularly of a process for preparing a chlorohydrin by reacting a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof with a chlorinating agent wherein the polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof that is used comprises at least one chloride and/or a sodium and/or potassium sulphate and in which the separating operation intended to remove part of the metal salt is a filtering operation. Particular mention is also made of a process for preparing a chlorohydrin wherein (a) a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof is subjected to reaction with a chlorinating agent in a reaction mixture, (b) continuously or periodically, a fraction of the reaction mixture containing at least water and the chlorohydrin is removed, (c) at least a part of the fraction obtained in step (b) is introduced into a distillation step and (d) the reflux ratio of the distillation step is controlled by providing water to the said distillation step. Mention is made very particularly of a process for preparing a chlorohydrin wherein (a) a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof is subjected to reaction with hydrogen chloride in a reaction mixture, (b) continuously or periodically, a fraction of the reaction mixture containing at least water and chlorohydrin is removed, (c) at least part of the fraction obtained in step (b) is introduced into a distillation step in which the ratio between the hydrogen chloride concentration and the water concentration in the fraction introduced into the distillation step is smaller than the hydrogen chloride/water concentration ratio in the binary azeotropic hydrogen chloride/water composition at the distillation temperature and pressure.

In the process for preparing a chlorohydrin according to the invention, the separation of the chlorohydrin and of the other compounds from the reaction mixture from chlorination of the polyhydroxylated aliphatic hydrocarbon may be carried out in accordance with methods as described in the application entitled “Process for preparing a chlorohydrin” filed in the name of SOLVAY SA on the same day as the present application and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing a chlorohydrin which comprises the following steps: (a) a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof is reacted with a chlorinating agent and an organic acid so as to give a mixture containing the chlorohydrin and esters of the chlorohydrin, (b) at least part of the mixture obtained in (a) is subjected to one or more treatments subsequent to step (a), and (c) the polyhydroxylated aliphatic hydrocarbon is added to at least one of the steps subsequent to step (a), in order to react at a temperature greater than or equal to 20° C. with the esters of the chlorohydrin, so as to form, at least partly, esters of the polyhydroxylated aliphatic hydrocarbon. Mention is made more particularly of a process in which the polyhydroxylated aliphatic hydrocarbon is glycerol and the chlorohydrin is dichloropropanol.

In the process for preparing a chlorohydrin according to the invention, the separation of the chlorohydrin and the other compounds from the reaction mixture from chlorination of the polyhydroxylated aliphatic hydrocarbon may be carried out in accordance with methods as described in the application entitled “Process for preparing a chlorohydrin starting from a polyhydroxylated aliphatic hydrocarbon”, filed in the name of SOLVAY SA on the same day as the present application, and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing chlorohydrin by reacting a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof with a chlorinating agent in a reactor which is supplied with one or more liquid streams containing less than 50% by weight of the polyhydroxylated aliphatic hydrocarbon, of the ester of polyhydroxylated aliphatic hydrocarbon or of the mixture thereof relative to the weight of the entirety of the liquid streams introduced into the reactor. More particular mention is made of a process comprising the following steps: (a) a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof is reacted with a chlorinating agent so as to give at least one mixture containing the chlorohydrin, water and the chlorinating agent, (b) at least a fraction of the mixture formed in step (a) is removed, and (c) the fraction removed in step (b) is subjected to an operation of distillation and/or stripping wherein the polyhydroxylated aliphatic hydrocarbon is added in order to isolate, from the fraction removed in step (b), a mixture containing water and the chlorohydrin and exhibiting a reduced chlorinating agent content as compared with the fraction removed in step (b).

In the process for preparing a chlorohydrin according to the invention, the separation of the chlorohydrin and of the other compounds from the reaction mixture from chlorination of the polyhydroxylated aliphatic hydrocarbon may be carried out in accordance with methods as described in the application entitled “Process for converting polyhydroxylated aliphatic hydrocarbons into chlorohydrins”, filed in the name of SOLVAY SA on the same day as the present application, and the content of which is incorporated here by reference. Particular mention is made of a process for preparing a chlorohydrin that comprises the following steps: (a) a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof is reacted with a chlorinating agent so as to give a mixture containing the chlorohydrin, chlorohydrin esters and water, (b) at least a fraction of the mixture obtained in step (a) is subjected to a distillation and/or stripping treatment so as to give a portion concentrated in water, in chlorohydrin and in chlorohydrin esters, and (c) at least a fraction of the portion obtained in step (b) is subjected to a separating operation in the presence of at least one additive so as to obtain a moiety concentrated in chlorohydrin and in chlorohydrin esters and containing less than 40% by weight of water.

The separating operation is more particularly a decantation.

In the process for preparing a chlorohydrin according to the invention, the isolation and the treatment of the other compounds of the reaction mixture may be carried out in accordance with methods as described in the application entitled “Process for preparing a chlorohydrin by chlorinating a polyhydroxylated aliphatic hydrocarbon”, filed in the name of SOLVAY SA on the same day as the present application. A preferred treatment consists in subjecting a fraction of the by-products of the reaction to a high-temperature oxidation.

Particular mention is made of a process for preparing a chlorohydrin that comprises the following steps: (a) a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof whose alkali metal and/or alkaline earth metal content is less than or equal to 5 g/kg, a chlorinating agent and an organic acid are reacted so as to give a mixture containing at least the chlorohydrin and by-products, (b) at least a portion of the mixture obtained in step (a) is subjected to one or more treatments in steps subsequent to step (a), and (c) at least one of the steps subsequent to step (a) consists in an oxidation at a temperature greater than or equal to 800° C. More particular mention is made of a process wherein, in the subsequent step, a portion of the mixture obtained in step (a) is removed and this portion is subjected to oxidation at a temperature greater than or equal to 800° C. in the course of the removal. Particular mention is also made of a process wherein the treatment of step (b) is a separating operation selected from phase separation, filtration, centrifugation, extraction, washing, evaporation, stripping, distillation, and adsorption operations or the combinations of at least two of these operations.

In the process according to the invention, when the chlorohydrin is chloropropanol, it is generally employed in the form of a mixture of compounds comprising the isomers of 1-chloropropan-2-ol and 2-chloropropan-1-ol. This mixture generally contains more than 1% by weight of the two isomers, preferably more than 5% by weight and particularly more than 50%. The mixture commonly contains less than 99.9% by weight of the two isomers, preferably less than 95% by weight and more particularly less than 90% by weight. The other constituents of the mixture may be compounds originating from the processes for preparing the chloropropanol, such as residual reactants, reaction by-products, solvents and, in particular, water.

The mass ratio of the isomers, 1-chloropropan-2-ol and 2-chloropropan-1-ol, is commonly greater than or equal to 0.01, preferably greater than or equal to 0.4. This ratio is commonly less than or equal to 99 and preferably less than or equal to 25.

In the process according to the invention, when the chlorohydrin is chloroethanol, it is generally employed in the form of a mixture of compounds comprising the 2-chloroethanol isomer. This mixture generally contains more than 1% by weight of the isomer, preferably more than 5% by weight and particularly more than 50%. The mixture commonly contains less than 99.9% by weight of the isomer, preferably less than 95% by weight and more particularly less than 90% by weight. The other constituents of the mixture may be compounds originating from the processes for preparing the chloroethanol, such as residual reactants, reaction by-products, solvents and, in particular, water.

In the process according to the invention, when the chlorohydrin is chloropropanediol, it is generally employed in the form of a mixture of compounds comprising the isomers of 1-chloropropane-2,3-diol and 2-chloropropane-1,3-diol. This mixture generally contains more than 1% by weight of the two isomers, preferably more than 5% by weight and particularly more than 50%. The mixture commonly contains less than 99.9% by weight of the two isomers, preferably less than 95% by weight and more particularly less than 90% by weight. The other constituents of the mixture may be compounds originating from the processes for preparing the chloropropanediol, such as residual reactions, reaction by-products, solvents and, in particular, water.

The mass ratio between the 1-chloropropane-2,3-diol and 2-chloropropane-1,3-diol isomers is commonly greater than or equal to 0.01, preferably greater than or equal to 0.4. This ratio is commonly less than or equal to 99 and preferably less than or equal to 25. In the process according to the invention, when the chlorohydrin is dichloropropanol, it is generally employed in the form of a mixture of compounds comprising the isomers of 1,3-dichloropropan-2-ol and 2,3-dichloropropan-1-ol. This mixture generally contains more than 1% by weight of the two isomers, preferably more than 5% by weight and in particular more than 50%. The mixture commonly contains less than 99.9% by weight of the two isomers, preferably less than 95% by weight and more particularly less than 90% by weight. The other constituents of the mixture may be compounds originating from the processes for preparing the dichloropropanol, such as residual reactants, reaction by-products, solvents and, in particular, water.

The mass ratio between the 1,3-dichloropropan-2-ol and 2,3-dichloropropan-1-ol isomers is commonly greater than or equal to 0.01, often greater than or equal to 0.4, frequently greater than or equal to 1.5, preferably greater than or equal to 3.0, more preferably greater than or equal to 7.0 and with very particular preference greater than or equal to 20.0. This ratio is commonly less than or equal to 99 and preferably less than or equal to 25.

In the process for preparing a chlorohydrin according to the invention, the reaction of chlorinating the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon or the mixture thereof with the chlorinating agent may be carried out in the presence of an organic acid. The organic acid may be a product originating from the process for preparing the polyhydroxylated aliphatic hydrocarbon or a product not originating from this process. In this latter case the product in question may be an organic acid which is used in order to catalyse the reaction of the polyhydroxylated aliphatic hydrocarbon with the chlorinating agent. The organic acid may also be a mixture of an organic acid originating from the process for preparing the polyhydroxylated aliphatic hydrocarbon, and an organic acid not originating from the process for preparing the polyhydroxylated aliphatic hydrocarbon.

In the process according to the invention the esters of the polyhydroxylated aliphatic hydrocarbon may originate from the reaction between the polyhydroxylated aliphatic hydrocarbon and the organic acid, before, during or within the steps which follow the reaction with the chlorinating agent.

The chlorohydrin obtained in the process according to the invention may include a heightened amount of halogenated ketones, in particular of chloroacetone, as described in the patent application FR 05.05120 of May 20, 2005, filed in the name of the applicant, and the content of which is incorporated here by reference. The halogenated ketone content may be reduced by subjecting the chlorohydrin obtained in the process according to the invention to an azeotropic distillation in the presence of water or by subjecting the chlorohydrin to a dehydrochlorination treatment as described in this application from page 4 line 1 to page 6 line 35.

Particular mention is made of a process for preparing an epoxide wherein halogenated ketones are formed as by-products and which comprises at least one treatment of removal of at least a portion of the halogenated ketones formed. Mention is made more particularly of a process for preparing an epoxide by dehydrochlorinating a chlorohydrin of which at least one fraction is prepared by chlorinating a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof, a treatment of dehydrochlorination and a treatment by azeotropic distillation of a water/halogenated ketone mixture, which are intended to remove at least a portion of the halogenated ketones formed, and a process for preparing epichlorohydrin wherein the halogenated ketone formed is chloroacetone.

The chlorohydrin obtained in the process according to the invention may be subjected to a dehydrochlorination reaction in order to produce an epoxide, as described in the patent applications WO 2005/054167 and FR 05.05120, both filed in the name of SOLVAY SA.

The term “epoxide” is used herein to describe a compound containing at least one oxygen bridged on a carbon-carbon bond. Generally speaking, the carbon atoms of the carbon-carbon bond are adjacent and the compound may contain atoms other than carbon atoms and oxygen atoms, such as hydrogen atoms and halogens. The preferred epoxides are ethylene oxide, propylene oxide and epichlorohydrin.

The dehydrochlorination of the chlorohydrin may be carried out as described in the application entitled “Process for preparing an epoxide starting from a polyhydroxylated aliphatic hydrocarbon and a chlorinating agent”, filed in the name of SOLVAY SA on the same day as the present application, and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing an epoxide wherein a reaction mixture resulting from the reaction between a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof with a chlorinating agent, the reaction mixture containing at least 10 g of chlorohydrin per kg of reaction mixture, is subjected to a subsequent chemical reaction without intermediate treatment.

Mention is also made of the preparation of an epoxide that comprises the following steps: (a) a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof is reacted with a chlorinating agent and an organic acid so as to form the chlorohydrin and chlorohydrin esters in a reaction mixture containing the polyhydroxylated aliphatic hydrocarbon, the ester of polyhydroxylated aliphatic hydrocarbon, water, the chlorinating agent and the organic acid, the reaction mixture containing at least 10 g of chlorohydrin per kg of reaction mixture, (b) at least a fraction of the reaction mixture obtained in step (a), this fraction having the same composition as the reaction mixture obtained in step (a), is subjected to one or more treatments in steps subsequent to step (a), and (c) a basic compound is added to at least one of the steps subsequent to step (a) in order to react at least partly with the chlorohydrin, the chlorohydrin esters, the chlorinating agent and the organic acid so as to form the epoxide and salts.

The process for preparing the chlorohydrin according to the invention may be integrated within an overall plan for preparation of an epoxide, as described in the application entitled “Process for preparing an epoxide starting from a chlorohydrin”, filed in the name of SOLVAY SA on the same day as the present application, and the content of which is incorporated here by reference.

Particular mention is made of a process for preparing an epoxide that comprises at least one step of purification of the epoxide formed, the epoxide being at least partly prepared by a process of dehydrochlorinating a chlorohydrin, the latter being at least partly prepared by a process of chlorinating a polyhydroxylated aliphatic hydrocarbon, an ester of a polyhydroxylated aliphatic hydrocarbon or a mixture thereof.

In the process for preparing a chlorohydrin according to the invention, the other step is for example a step of storage, supply, withdrawal, transfer, chemical treatment or physical treatment of compounds used or products in the process for preparing the chlorohydrin. Examples of these steps have been described above.

Among the steps of storage mention may be made, for example, of the storage of the chlorinating agent containing the hydrogen chloride, and of the polyhydroxylated aliphatic hydrocarbon, before use, the storage of purges before treatment, the storage of the chlorohydrin produced, the storage of the catalyst and of its preparations. Among the steps of chemical treatment mention may be made, for example, of a hydrolysis treatment intended to recover the catalyst, and a dissolution treatment of the catalyst. Among the steps of physical treatment mention may be made, for example, of the operations of separation by stripping, distillation, evaporation, extraction, decantation and filtration and of the operations of heat exchange, heating and cooling.

Among the steps of supply, withdrawal or transfer mention may be made, for example, of the operations of recycling, purging and discharging effluents, the transport of fluids between the various pieces of apparatus in which the chemical reactions, the storage and the chemical and physical treatments are carried out.

In the process for preparing a chlorohydrin according to the invention, “apparatus” refers to the containers in which compounds are stored, chemical reactions are carried out and/or physical operations are carried out, the pipes and connectors connecting these containers, elements ensuring that the connectors are leaktight, instruments necessary for the transfer of compounds between the containers, instruments and equipment for measuring the various parameters necessary for the monitoring of the storage, for the transfer of the compounds and for the carrying-out of the chemical reactions and the physical operations.

The temperature and pressure conditions to which this apparatus is subject depend on their use in the process.

Certain apparatus is used at low temperature. By low temperature is meant a temperature which is less than or equal to 110° C., often less than or equal to 100° C. and more particularly less than or equal to 95° C. This low temperature is generally greater than or equal to 0° C., frequently greater than or equal to 5° C. and more particularly greater than or equal to 10° C. Apparatus used at low temperature includes, for example, apparatus for storing acidic raw materials and the chlorohydrin produced, and the phase separators.

Certain apparatus is used at high temperature. By high temperature is meant a temperature which is greater than 110° C. This high temperature is generally less than or equal to 200° C., frequently less than or equal to 160° C. and more particularly less than or equal to 140° C. Apparatus used at high temperature includes, for example, the reactors in which the reaction of chlorinating the polyhydroxylated aliphatic hydrocarbon, the treatment of purges, the recovery of the catalyst and the preparation of the catalyst are carried out, the heat exchangers and the devices for separation by stripping, distillation, evaporation, extraction and filtration.

Certain apparatus is used at low pressure. By low pressure is meant a pressure which is less than or equal to 3 bar absolute, often less than or equal to 2 bar and more particularly less than or equal to 1.5 bar. This low pressure is generally greater than or equal to 0.01 bar absolute, frequently greater than or equal to 0.05 bar and with more particular preference greater than or equal to 0.1 bar. Apparatus used at low pressure includes, for example, the devices for separation by stripping, distillation, evaporation, extraction and filtration.

Certain apparatus is used at high pressure. By high pressure is meant a pressure which is greater than 3 bar absolute, often greater than or equal to 5 bar and more particularly greater than or equal to 7 bar. This high pressure is generally less than or equal to 50 bar absolute, frequently less than or equal to 20 bar and with more particular preference less than or equal to 10 bar. Apparatus used at high pressure includes, for example, the reactors in which the reaction of chlorinating the polyhydroxylated aliphatic hydrocarbon is carried out, and devices for separation by stripping, distillation, evaporation and filtration.

The apparatus may be covered with or made of material which is resistant to the chlorinating agents under the conditions in which this apparatus operates. Besides the operating conditions of temperature and of pressure referred to above, the selection of the type of protection, by covering with or by manufacture from a material which is resistant to the chlorinating agents, depends on numerous factors associated with the chlorinating agent, with the nature and the method of implementation of the material which is resistant to chlorinating agents, and with the characteristics of the apparatus to be protected.

The factors associated with the chlorinating agent are for example its chemical nature (chlorine, hydrogen chloride), its physical state (liquid, gas, in aqueous solution) and its purity (presence of water).

The factors associated with the apparatus are for example the shape, the size, the complexity and the surface access of the apparatus to be protected.

The materials as disclosed as described in application WO 2005/054167 of SOLVAY SA, on page 6 lines 3 to 23, are particularly preferred.

As appropriate material mention may be made, for example, of metallic materials and non-metallic materials.

These materials may be used either within the mass, or in the form of cladding, or else by any coating process.

Among the metallic materials, mention may be made of tantalum and tantalum alloys, zirconium and zirconium alloys, titanium and titanium alloys, platinum and the metals of the “platinum” group, silver and silver-gold-palladium alloys with a minimum of 30% gold, gold and gold-silver alloys and gold-platinum alloys, molybdenum and molybdenum alloys, nickel-molybdenum alloys, nickel-chromium-molybdenum alloys, copper alloys (silicon bronze), copper-tantalum and copper-niobium alloys, tin-antimony alloys containing 5% antimony, tin-nickel alloys, niobium and niobium-tantalum alloys.

Among the metals of the platinum group mention may be made of rhodium iridium, ruthenium, palladium and osmium.

Among the metallic materials, gold and tantalum are preferred.

The metals and their alloys may be used either within the mass or in the form of cladding, or else by any coating process.

Among the non-metallic materials mention may be made of high-density polyethylene, fluoroelastomer-based elastomers, thermoplastics based on polypropylene, on fluoro polymers, ABS (acrylonitrile-butadiene-styrene) copolymers, acrylonitrile (40%)-vinyl chloride (60%) copolymer, polysulphones, polyphenylene sulphides and polyphenyl sulphones, glass-resin laminates based on polyester resins, on phenolic resins, on furan resins, on epoxy resins and on vinyl ester resins, ceramics based on alumina and corundum, metalloceramic materials based on hafnium carbide and titanium nitride, refractory materials based on silicon carbide, on silica, on high-silica-content aluminium silicates, on zirconium silicate, on zirconium oxide and on sillimanite (Al₂O₃—SiO₂), coatings based on epoxy resin, on Sakaphen, on Brauthite on the basis of phenol-formaldehyde resin and of isolemail, acid-resistant cements based on silicates, on phenol-formaldehyde resin and on sulphide mixed with quartz sand, self-curing acid-resistant cements based on phenol-formaldehyde resins admixed with graphite, furfuryl alcohol resins admixed with graphite, epoxy resins admixed with carbon and polyester resins admixed with quartz. In the case of the cements the substrate should be protected by an additional plastic sheet. Impregnated graphite (impregnated with polytetrafluoroethylene), carbon, glass, quartz, enamel, porcelain, earthenware and acid-resistant brick may also be suitable as non-metallic materials.

The enamel may be used as a material for coating the steel, and the material which is resistant to the chlorinating agents is enameled steel.

Among the polymers, those highly suitable include polyolefins such as high-density polyethylene and polypropylene and in particular, thermoplastics based on fluoropolymers, sulphur-containing polymers such as polysulphones or polysulphides, especially aromatic polymers of this kind, and graphite and impregnated graphite.

Among the thermoplastics based on fluoropolymers, those highly suitable include polyvinylidene fluoride, polytetrafluoroethylene, perfluoroalkoxyalkanes, ethylene-tetrafluoroethylene copolymers, tetrafluoroethylene-perfluoromethyl vinyl ether copolymers and tetrafluoroethylene-hexafluoropropylene copolymers.

The polymers may be employed in the solid state or reinforced with a jacket (steel, hooped reinforcement).

Among the coatings formed by means of resins, those based on epoxy resins or on phenolic resins are especially suitable.

For certain particular elements, for example heat exchangers and pumps, graphite, whether impregnated or not, is especially suitable. For the heat exchangers which allow heating or evaporation of the fluids in the process, impregnation with polytetrafluoroethylene is especially suitable.

Enameled steel, tantalum, gold and perfluorinated polymers are highly suitable for the coating or manufacture of apparatus operating at high temperature.

Polyolefins, fluoropolymers and metal alloys are highly suitable for the coating or manufacture of apparatus operating at low temperature.

In the process, use and plant according to the invention, the polyhydroxylated aliphatic hydrocarbon is preferably glycerol and the chlorohydrin is preferably dichloropropanol.

When the chlorohydrin is dichloropropanol, the process according to the invention may be followed by the preparation of epichlorohydrin by dehydrochlorinating dichloropropanol, and the epichlorohydrin may be used in the preparation of epoxy resins.

The examples below are intended to illustrate the invention, but without imposing any limitation thereon.

EXAMPLE 1 Not in Accordance with the Invention

Corrosion test specimens made of Ti Gr 26 t and Monel 400 were placed at 120° C. for 90 days in a liquid, glycerol hydrochlorination reaction mixture composed of 20% dichloropropanol, 18% glycerol monochlorohydrin, 2% glycerol, 6% mono- and polychlorinated glycerol oligomers, 6% water, 0.8% HCl, the remainder being composed of the carboxylic acid serving as catalyst and of its esters. The test specimens dissolved completely in the reaction mixture.

EXAMPLE 2 In Accordance with the Invention

Immersed in the reaction mixture in liquid phase, the elements of enameled steel from the reactor for hydrochlorinating the glycerol, those made of graphite from the heat exchangers, and those made of PTFE from the distillation columns showed no sign of corrosion. 

1. A process for preparing dichloropropanol, comprising (a) reacting glycerol, an ester of glycerol or a mixture thereof with a chlorinating agent comprising hydrogen chloride, and (b) at least one other step, carried out in apparatus made from or covered with a material resistant to the chlorinating agent under the conditions in which this step is realized, wherein the at least one other step is a step of storage, supply, withdrawal, transfer, chemical treatment, or of physical treatment selected from the physical operations of separation by stripping, distillation, evaporation, extraction, decantation and filtration, of one or more compounds used in and/or produced in the process for preparing the dichloropropanol, and wherein the material resistant to the chlorinating agent is selected from one or more of tantalum, tantalum alloys, zirconium, zirconium alloys, titanium, titanium alloys, platinum and the metals of the platinum group, silver and silver-gold-palladium alloys with a minimum of 30% gold, gold and gold-silver alloys and gold-platinum alloys, molybdenum, copper-tantalum and copper-niobium alloys, tin-antimony alloys containing 5% antimony, tin-nickel alloys, niobium and niobium-tantalum alloys, enamel, high-density polyethylene, fluoroelastomer-based elastomers, thermoplastics based on polypropylene, on fluoro polymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile (40%)-vinyl chloride (60%) copolymer, polysulphones, polyphenylene sulphides and polyphenyl sulphones, glass-resin laminates based on polyester resins, on phenolic resins, on furan resins, and on epoxy resins, ceramics based on alumina and corundum, metalloceramic materials based on hafnium carbide and titanium nitride, refractory materials based on silicon carbide, on silica, on high-silica-content aluminium silicates, on zirconium silicate, on zirconium oxide and on sillimanite (Al₂O₃—SiO₂), coatings based on phenol-formaldehyde resin, acid-resistant cements based on silicates, on phenol-formaldehyde resin and on sulphide mixed with quartz sand, self-curing acid-resistant cements based on phenol-formaldehyde resins admixed with graphite, furfuryl alcohol resins admixed with graphite, epoxy resins admixed with carbon, polyester resins admixed with quartz, graphite, impregnated graphite, quartz, porcelain, earthenware and acid-resistant brick.
 2. The process according to claim 1, wherein the glycerol, the ester of glycerol or the mixture thereof is obtained starting from renewable raw materials.
 3. The process according to claim 1, wherein the hydrogen chloride is gaseous hydrogen chloride.
 4. The process according to claim 1, wherein the other step is a step of storage, supply, withdrawal, transfer, or chemical treatment.
 5. The process according to claim 1, wherein the apparatus is selected from containers in which compounds are stored, chemical reactions are carried out and/or said physical operations are carried out, the pipes and connectors connecting these containers, elements ensuring that the lines are leaktight, instruments necessary for the transfer of compounds between the containers, instruments and equipment for measuring the various parameters necessary for the monitoring of the storage, for the transfer of the compounds and for the carrying-out of the chemical reactions and the physical operations.
 6. The process according to claim 1, wherein the apparatus are maintained at a temperature greater than or equal to 0° C. and less than or equal to 200° C. and at a pressure greater than or equal to 0.01 bar absolute and less than or equal to 50 bar.
 7. The process according to claim 1, wherein the material resistant to the chlorinating agent is selected from tantalum and tantalum alloys, zirconium and zirconium alloys, titanium and titanium alloys, platinum and the metals of the platinum group, silver and silver-gold-palladium alloys with a minimum of 30% gold, gold and gold-silver alloys and gold-platinum alloys, molybdenum copper-tantalum and copper-niobium alloys, tin-antimony alloys containing 5% antimony, tin-nickel alloys, and niobium and niobium-tantalum alloys.
 8. The process according to claim 1, wherein the material resistant to the chlorinating agent is selected from enamel, high-density polyethylene, fluoroelastomer-based elastomers, thermoplastics based on polypropylene, on fluoro polymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile (40%)-vinyl chloride (60%) copolymer, polysulphones, polyphenylene sulphides and polyphenyl sulphones, glass-resin laminates based on polyester resins, on phenolic resins, on furan resins, and on epoxy resins, ceramics based on alumina and corundum, metalloceramic materials based on hafnium carbide and titanium nitride, refractory materials based on silicon carbide, on silica, on high-silica-content aluminium silicates, on zirconium silicate, on zirconium oxide and on sillimanite (Al₂O₃—SiO₂), coatings based on phenol-formaldehyde resin, acid-resistant cements based on silicates, on phenol-formaldehyde resin and on sulphide mixed with quartz sand, self-curing acid-resistant cements based on phenol-formaldehyde resins admixed with graphite, furfuryl alcohol resins admixed with graphite, epoxy resins admixed with carbon and polyester resins admixed with quartz, graphite, impregnated graphite, quartz, porcelain, earthenware and acid-resistant brick.
 9. The process according to claim 8, wherein the material resistant to the chlorinating agent is selected from enamel, high-density polyethylene, polypropylene, thermoplastics based on fluoropolymers, polysulphones and polysulphides, graphite and impregnated graphite.
 10. The process according to claim 9, wherein the material resistant to the chlorinating agent is a fluoropolymer-based thermoplastic selected from polyvinylidene fluoride, polytetrafluoroethylene, perfluoroalkoxyalkanes, ethylene-tetrafluoroethylene copolymers, tetrafluoroethylene-perfluoromethyl vinyl ether copolymers and tetrafluoroethylene-hexafluoropropylene copolymers.
 11. The process according to claim 9, wherein the material resistant to the chlorinating agent is enamel on steel.
 12. The process according to claim 1, followed by preparation of epichlorohydrin by dehydrochlorination of dichloropropanol.
 13. The process according to claim 12, wherein the epichlorohydrin is used in the preparation of epoxy resins.
 14. The process according to claim 1 all of the steps of the process are carried out in apparatus made from or covered with materials which are resistant to the chlorinating agents under the conditions in which these steps are carried out.
 15. The process according to claim 1, wherein the at least one other step is a step of physical treatment selected from the physical operations of separation by stripping, distillation, and evaporation.
 16. The process according to claim 1, wherein the material resistant to the chlorinating agent is selected from tantalum, titanium and titanium alloys.
 17. The process according to claim 1, wherein the material resistant to the chlorinating agent is tantalum.
 18. The process according to claim 1, wherein the material resistant to the chlorinating agent is silicon carbide.
 19. The process according to claim 1, wherein the material resistant to the chlorinating agent is selected from graphite and impregnated graphite.
 20. The process according to claim 1, wherein the material resistant to the chlorinating agent is graphite impregnated with polytetrafluoroethylene.
 21. The process according to claim 1, wherein the material resistant to the chlorinating agent is selected from one or more of ceramics based on alumina, coatings based on phenol-formaldehyde resin, and porcelain.
 22. The process according to claim 1, wherein the material resistant to the chlorinating agent is selected from one or more of tantalum, titanium alloys, enamel, fluoroelastomer-based elastomers, fluoro polymers, glass-resin laminates based on polyester resins, silicon carbide, impregnated graphite and porcelain.
 23. The process according to claim 22, wherein the material resistant to the chlorinating agent is selected from one or more of graphite impregnated with polytetrafluoroethylene, enameled steel, polytetrafluoroethylene, and porcelain. 